How to use this image

All examples in this guide use the public image. If you've mirrored the repository for your own use (for example, to your Docker Hub namespace), update your commands to reference the mirrored image instead of the public one.

For example:

• Public image: dhi.io/<repository>:<tag>
• Mirrored image: <your-namespace>/dhi-<repository>:<tag>

For the examples, you must first use docker login dhi.io to authenticate to the registry to pull the images.

Start a MediaWiki instance

The Docker Hardened MediaWiki image is based on the Docker Hardened PHP image PHP-FPM flavor. It is designed to run alongside a web server such as Nginx or Apache. To run a basic MediaWiki instance with the Docker Hardened MediaWiki image, use the following Docker Compose file:

services:
   mediawiki:
      image: dhi.io/mediawiki:<tag>
      volumes:
         - document-root:/var/www/html
         - data:/var/www/data

   nginx:
      image: dhi.io/nginx:1-debian13
      ports:
         - "80:80"
      depends_on:
         - mediawiki
      volumes:
         - document-root:/var/www/html:ro
         - ./nginx.conf:/etc/nginx/conf.d/default.conf:ro

volumes:
   document-root:
   data:

The Nginx configuration file (nginx.conf) should include the following basic configuration for MediaWiki:

server {
    listen 80;

    # this config assumes that MediaWiki is installed into /var/www/html,
    # so LocalSettings.php would be located at /var/www/html/LocalSettings.php
    root /var/www/html;
    index index.php;

    # allow larger file uploads and longer script runtimes
    client_max_body_size 100m;
    client_body_timeout 60;

    # Uncomment the following code if you wish to use the installer/updater
    # installer/updater
    location /mw-config/ {
        # Do this inside of a location so it can be negated
        location ~ \.php$ {
            include fastcgi_params;
            fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
            fastcgi_pass mediawiki:9000;
            fastcgi_index index.php;
        }
    }

    # Location for wiki's entry points
    location ~ ^/(index|load|api|thumb|opensearch_desc|rest|img_auth)\.php$ {
        include fastcgi_params;
        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
        fastcgi_pass mediawiki:9000;
        fastcgi_index index.php;
    }

    # Images
    location ~ ^/(mw-config)?/images/ {
        # Separate location for images/ so .php execution won't apply
        add_header X-Content-Type-Options "nosniff";
    }
    location /images/deleted {
        # Deny access to deleted images folder
        deny all;
    }
    # MediaWiki assets (usually images)
    location ~ ^/resources/(assets|lib|src) {
        try_files $uri 404;
        add_header Cache-Control "public";
        expires 7d;
    }
    # Assets, scripts and styles from skins and extensions
    location ~ ^/(skins|extensions)/.+\.(css|js|gif|jpg|jpeg|png|svg|wasm)$ {
        try_files $uri 404;
        add_header Cache-Control "public";
        expires 7d;
    }
    # License and credits files
    location ~ ^/(COPYING|CREDITS) {
        default_type text/plain;
    }

    # Handling for Mediawiki REST API, see [[mw:API:REST_API]]
    location /rest.php/ {
        try_files $uri $uri/ /rest.php?$query_string;
    }

    # Uncomment the following code for handling image authentication
    # Also add "deny all;" in the location for /images above
    #location /img_auth.php/ {
    #    try_files $uri $uri/ /img_auth.php?$query_string;
    #}

    # Handling for the article path (pretty URLs)
    location /wiki/ {
        rewrite ^/wiki/(?<pagename>.*)$ /index.php;
    }

    # Allow robots.txt in case you have one
    location = /robots.txt {
    }
    # Explicit access to the root website, redirect to main page (adapt as needed)
    location = / {
        return 301 /wiki/Main_Page;
    }

    # Every other entry point will be disallowed.
    # Add specific rules for other entry points/images as needed above this
    location / {
        return 404;
    }
}

Then start the services with:

docker-compose up -d

You can browse to http://localhost to access the MediaWiki instance and start the configuration. Once your are done configuring, download the LocalSettings.php file, update the Docker Compose file to mount it into the container, and restart the services.

   mediawiki:
      image: dhi.io/mediawiki:<tag>
      volumes:
         - document-root:/var/www/html
         - data:/var/www/data
         - ./LocalSettings.php:/var/www/html/LocalSettings.php:ro # <-- Add this line

Then restart the container.

docker-compose up -d

Note that whenever you update the LocalSettings.php file, you need to restart the container to apply the changes. This is because PHP uses opcode caching.

Non-hardened images vs Docker Hardened Images

Key differences

The following section is pre-written to apply to all images. Add any additional features that Engineering notes in their template.

Why no shell or package manager?

The following section is pre-written to apply to all images.

Docker Hardened Images prioritize security through minimalism:

• Reduced attack surface: Fewer binaries mean fewer potential vulnerabilities
• Immutable infrastructure: Runtime containers shouldn't be modified after deployment
• Compliance ready: Meets strict security requirements for regulated environments

The hardened images intended for runtime don't contain a shell nor any tools for debugging. Common debugging methods for applications built with Docker Hardened Images include:

• Docker Debug⁠ to attach to containers
• Docker's Image Mount feature to mount debugging tools
• Ecosystem-specific debugging approaches

Docker Debug provides a shell, common debugging tools, and lets you install other tools in an ephemeral, writable layer that only exists during the debugging session.

For example, you can use Docker Debug:

docker debug <image-name>

or mount debugging tools with the Image Mount feature:

docker run --rm -it --pid container:my-image \
  --mount=type=image,source=dhi.io/busybox,destination=/dbg,ro \
  dhi.io/<image-name>:<tag> /dbg/bin/sh

Image variants

The following section is pre-written to apply to all images. If engineering notes image-specific notes, add them as needed.

Docker Hardened Images come in different variants depending on their intended use.

Runtime variants are designed to run your application in production. These images are intended to be used either directly or as the FROM image in the final stage of a multi-stage build. These images typically:

• Run as the nonroot user
• Do not include a shell or a package manager
• Contain only the minimal set of libraries needed to run the app

Build-time variants typically include dev in the variant name and are intended for use in the first stage of a multi-stage Dockerfile. These images typically:

• Run as the root user
• Include a shell and package manager
• Are used to build or compile applications

FIPS variants include fips in the variant name and tag. They come in both runtime and build-time variants. These variants use cryptographic modules that have been validated under FIPS 140, a U.S. government standard for secure cryptographic operations. For example, usage of MD5 fails in FIPS variants.

Compat variants

Only include this section if this image has compat variants

Compat variants support more seamless usage of DHI as a drop-in replacement for upstream images, particularly for circumstances that the ultra-minimal runtime variant may not fully support. These images typically:

• Run as the nonroot user
• Improve compatibility with upstream helm charts
• Include optional tools that are critical for certain use-cases"

Migrate to a Docker Hardened Image

The following section is pre-written to apply to all image migrations. If engineering notes image-specific migration steps, items, notes, etc. add them to this section as needed.

To migrate your application to a Docker Hardened Image, you must update your Dockerfile. At minimum, you must update the base image in your existing Dockerfile to a Docker Hardened Image. This and a few other common changes are listed in the following table of migration notes:

The following steps outline the general migration process.

1. Find hardened images for your app.

   A hardened image may have several variants. Inspect the image tags and find the image variant that meets your needs.

2. Update the base image in your Dockerfile.

   Update the base image in your application's Dockerfile to the hardened image you found in the previous step. For framework images, this is typically going to be an image tagged as dev because it has the tools needed to install packages and dependencies.

3. For multi-stage Dockerfiles, update the runtime image in your Dockerfile.

   To ensure that your final image is as minimal as possible, you should use a multi-stage build. All stages in your Dockerfile should use a hardened image. While intermediary stages will typically use images tagged as dev, your final runtime stage should use a non-dev image variant.

4. Install additional packages

   Docker Hardened Images contain minimal packages in order to reduce the potential attack surface. You may need to install additional packages in your Dockerfile. Inspect the image variants to identify which packages are already installed.

   Only images tagged as dev typically have package managers. You should use a multi-stage Dockerfile to install the packages. Install the packages in the build stage that uses a dev image. Then, if needed, copy any necessary artifacts to the runtime stage that uses a non-dev image.

   For Alpine-based images, you can use apk to install packages. For Debian-based images, you can use apt-get to install packages.

Troubleshoot migration

The following sections are pre-written and included with each image. If engineering notes additional migration troubleshooting steps, include them as a separate H3 section. If there are image-specific notes for pre-written migration troubleshooting sections, add them as needed.

General debugging

The hardened images intended for runtime don't contain a shell nor any tools for debugging. The recommended method for debugging applications built with Docker Hardened Images is to use Docker Debug⁠ to attach to these containers. Docker Debug provides a shell, common debugging tools, and lets you install other tools in an ephemeral, writable layer that only exists during the debugging session.

Permissions

By default image variants intended for runtime, run as the nonroot user. Ensure that necessary files and directories are accessible to the nonroot user. You may need to copy files to different directories or change permissions so your application running as the nonroot user can access them.

Privileged ports

Non-dev hardened images run as a nonroot user by default. As a result, applications in these images can't bind to privileged ports (below 1024) when running in Kubernetes or in Docker Engine versions older than 20.10.

No shell

By default, image variants intended for runtime don't contain a shell. Use dev images in build stages to run shell commands and then copy any necessary artifacts into the runtime stage. In addition, use Docker Debug to debug containers with no shell.

Entry point

Docker Hardened Images may have different entry points than images such as Docker Official Images. Use docker inspect to inspect entry points for Docker Hardened Images and update your Dockerfile if necessary.